1. Field of the Invention
The present invention relates to a coding apparatus and method, a decoding apparatus and method, a data processing system, a storage medium, and a signal. In particular, the invention relates to a coding apparatus and method, a decoding apparatus and method, a data processing system, a storage medium, and a signal which allow information to be embedded into data without deterioration in decoded data and without increase in data amount.
2. Background of the Invention
An example of a technique of embedding information without increasing the data amount is such that the LSB or the lowest two bits of digital audio data are converted to information to be embedded. In this technique, the fact that the lowest bit or bits of digital audio data do not much influence its sound quality is utilized and the lowest bit or bits of digital audio data are simply replaced by information to be embedded. Therefore, at the time of reproduction, information-embedded digital audio data is output as it is, that is, without returning the lowest bit or bits to the original state. That is, the digital audio data is output in a state that information is embedded therein because it is difficult to return the lowest bit or bits embedded information to the original state and the lowest bit or bits do not much influence the sound quality.
However, in the above technique, a signal that is different from the original signal is output. Therefore, influence occurs in the sound quality when the signal is audio data or in the image quality when the signal is video data.
An object of the present invention is to solve the foregoing problem.
In order to achieve the foregoing object, the present invention provides a coding apparatus for coding first data in accordance with second data, the coding apparatus comprising a memory for storing at last partial data of the first data, and a coding section for embedding data in relation to the second data into the first data by rotating the at least partial data stored in the memory in accordance with the second data.
In order to achieve the foregoing object, the present invention provides a decoding apparatus for decoding coded data in which first data has been coded in accordance with second data, the decoding apparatus comprising a rotation section for rotating at last partial data of the coded data; a correlation calculating section for calculating a correlation between the at least partial data rotated by the rotation section and peripheral data of the at least partial data; a second data decoding section for decoding the second data embedded in the coded data by determining a rotation amount of the at least partial data of the coded data rotated by the rotation section on the basis of the correlation obtained by the correlation calculating section; and first data decoding section for decoding the coded data to the original first data in accordance with the rotation amount determined by the second data decoding section.